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42 Cards in this Set
- Front
- Back
Nervous system |
Controls rapid activity like muscle movement with both electrical and chemical stimulation. Typically adjusts for short-term changes |
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Neurons |
Functional cells of nervous system. Relay messages to and from central nervous system |
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Glial cells |
Non-condensing cells that protect and support neurons. Binds nervous tissue to other structures, helps repair cells and protects nervous tissue |
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Dendrites |
Neuron fibers. Receive info from sensory receptors and other neurons. Conduct impulses toward the cell body of neuron. |
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Cell body of neuron |
Part of neuron with the nucleus and most of the cell's organelle |
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Axons |
Neurons fibers that conduct impulses away from the cell body of the neuron. Relay neural impulses to other neurons, muscles or glands. May be covered with myelin sheath |
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Myelin sheath |
Neuron insulation made of Schwann cells (glial cells) that wrap around the axon. Increases the rate of neural transmission |
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Nodes of Ranvier |
Small spaces between sections of myelin sheath that are important in speeding up the conduction of nerve impulses. |
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Neurilemma |
Thin coating formed by outermost layer of Schwann cells in peripheral nervous system. Plays a role in repair of damaged myelinated neurons |
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White matter |
Neurons in brain/spinal cord with myelinated sheaths |
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Grey matter |
Neurons in brain/spinal cord without myelinated sheaths. Not regenerated- damage is permanent |
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Multiple sclerosis |
Autoimmune disease where immune system attacks myelin sheath. Causes loss of muscle control and brain function. No cure, but can be treated with immunosuppressive drugs |
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Nerve |
Banded bundle of neurons with myelinated axon fibers |
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Sensory neuron |
Afferent neuron. In peripheral nervous system only. Relays info about environment, from sensory receptors to central nervous system for processing. Cell body in center of neuron |
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Interneuron |
Link between sensory and motor neurons. Only in central nervous system |
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Motor neuron |
Efferent neurons. Relays info from central nervous system to effectors |
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Effectors |
Any tissue or organ that carries out a command from the nervous system. Muscle or gland |
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Reflex arc |
Receptor to sensory neuron to interneuron (spinal cord) to effector. Simplest nerve pathway. Same stimulus leads to the same response |
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Electrical potential |
Force that causes charged particles to move- measured in volts. Occurs when charge on either side of a membrane varies |
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Sodium-potassium pump |
Specialized pump in the cell membranes. Moves potassium into cytoplasm while removing sodium from the cytoplasm. Requires ATP as it moves ions against the concentration gradient (low to high conc) |
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Number of Na+ and K+ moved in pump |
3 Na+ pumped outside the cell for every 2 K+ pumped into the cell |
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Diffusion channels |
Don't require ATP, as Na and K move with the concentration gradient. Na+ in and K+ out |
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Resting membrane potential |
-70 mV. Voltage difference across cell membrane when it is not transmitting nerve impulse. Membrane is polarized. Sodium diffusion channels are closed, some potassium are open. Net result: much greater negative charge inside the cell membrane |
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Action potential |
Viltage difference across a membrane when it is stimulated. Sodium diffusion channels open and potassium channels close. Positive charge inside the cell, negative outside- membrane depolarized. |
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Repolarization |
Original polarity of nerve cell membrane is restored. K+ channels open, Na+ close. Returns to resting potential |
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Refractory period |
Recovery time required for a nerve cell to become repolarized or to produce another action potential |
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Threshold level |
Minimum level of stimulus required to produce a response. Action potential won't occur unless polarity changes enough- different for every neuron |
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Neural transmission |
All or nothing response. Only one nerve impulse that doesn't increase or decrease in magnitude |
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Intensity of stimulus |
Indicated to brain by variations in frequency and number of impulses |
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Synapse |
Occurs when action potential is converted to chemical message and transmitted to another cell |
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Presynaptic neuron |
Neuron carrying the impulse to synapse |
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Postsynaptic neuron |
Neuron that carries impulses away from synapse |
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Stimulatory neurotransmittors |
Causes Na+ channels to open- depolarization |
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Inhibitory neurotransmitters |
Causes K+ channels to open- hyperpolarization occurs. Inhibits action potential |
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Summation |
Effect produced by accumulation of neurotransmitters from 2 or more neurons. Increased muscle contraction |
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Acetylcholine |
Neurotransmitter commonly found in brain and neuromuscular junctions. Stimulatory. Causes Na channels to open in postsynaptic neuron- depolarization |
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(Acetyl)cholinesterase |
Neurotransmitter/enzyme that is released following acetylcholine and destroys it. Long-term exposure leads to respiratory arrest |
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Norepinephrine (noradrenalin) |
Neurotransmitter that plays a role in the sympathetic nervous system to help induce the fight or flight response. |
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GABA |
Inhibitory neurotransmitter. Too little causes anxiety disorders |
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Glutamate |
Stimulatory neurotransmitter. Too much will kill neurons- Lou Gehrig's disease |
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Serotonin |
Neurotransmitter involved in emotion and mood. Too little causes depression |
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Dopamine |
Inhibitory neurotransmitter associated with feelings of pleasure. Excessive amounts associated with schizophrenia. Parkinson's disease with too little |